1. Field of the Invention
The present invention relates in general to a method of purifying combustion gases by removing or separating acid gases therefrom, a device for removing the acid gases, and an incinerator or a furnace having a function of purifying the combustion gases.
2. Discussion of the Related Art
Acid gases contained in combustion gases may be removed by a wet method or a dry method.
In the wet method, combustion gases are brought into contact with an alkali solution, so that acid gases contained in the combustion gases are absorbed by the alkali solution, and thus removed from the combustion gases.
In the dry method, the combustion gases are brought into contact with a solid alkali substance in the form of a powder or pellets, so that the acid gases react with the alkali substance, and are thereby removed from the combustion gases. For the combustion gases to be contacted with the alkali substance, a stream of combustion gases is introduced into a reaction device, in which a powdered or pulverized alkali substance is jetted into the combustion gas stream. Alternatively, the combustion gas stream is caused to flow through a container which is filled with a pelletized alkali substance.
The above methods known in the art to remove acid gases from the combustion gases, which use an alkali substance in the form of a solution, a powder or pellets, require an exclusive device for effecting a contact between the combustion gases and the acid gases, namely, a device adapted to inject an alkali solution or powder, or a container filled with a mass of alkali pellets. Accordingly, the equipment to remove the acid gases according to the above methods tend to be expensive.
In the art of removing the acid gases, it has been a long felt need to prolong an activity of reaction of alkali solution, powder or pellets with the acid gases. Since the reaction activity of the alkali substance is eventually lost as a result of neutralization of the alkali substance which reacted with the acid gases, the alkali solution used in the wet method is replaced with a fresh one when the solution is neutralized or saturated with the absorbed acid gases, or a mass of the powdered or pelletized alkali substance used in the dry method is replaced with a fresh one or changed into a reactive state, when the substance is neutralized or exhausted. An exclusive device is required to change the exhausted alkali solid into a reactive state.